A friend was asking me about the posibility to program a script that temporarily posted new content to a Blog. I didn't know that this wasn't necessary with a Wordpress Blog. I still haven't gone through the source code to confirm this, but apparently this is how it works:
To show the main page, Wordpress doesn't retrieve the last posts on the table. Instead it makes a cut by date from now to the past limiting the query to the amount of posts to be shown in a page. This seems pretty reasonable, I do not know if other engines do this as well. Not that I know of this I'd expect them to behave so.
This behavior allows to insert all the desired posts in the database with future dates. They will not be shown until thos future dates becom past dates :)